异相添加剂对超临界CO_2物性的影响分析  

Impact Analysis of Heterogeneous Additive on the Thermal Properties of Supercritical Carbon Dioxide

作　　者：李晓凤[1] 李敏霞[1] 马一太[1] 

机构地区：[1]天津大学中低温热能高效利用教育部重点实验室,热能工程系,天津300072

出　　处：《工程热物理学报》2013年第2期215-219,共5页Journal of Engineering Thermophysics

基　　金：国家自然科学基金资助项目(No.50976075)

摘　　要：为提高CO_2跨临界循环中膨胀机的效率,添加异相添加剂对其进行扰动,可缩短相变延迟。本文分析了异相添加剂NC对超临界CO_2物性影响。通过理论分析与计算,得出加入异相添加剂NC可以缩短相变延迟并能形成汽化核心,提高膨胀过程中的回收功。在远离临界区域时,异相添加剂NC对超临界CO_2的密度、黏度、比热容以及导热系数等热物性影响很小。并应用Gnielinski换热关联式计算微量NC添加剂在8 MPa时的换热,得出在超临界,尤其是远离临界点时,添加剂NC对超临界CO_2的换热几乎没有影响。To improve the expander efficiency in the CO2 trans-critical cycle, heterogeneous additive is adopted to disturb the expansion process and it can reduce the phase transition delay time. This paper analyses the impact of heterogeneous additive NC on the thermal property of supercritical carbon dioxide. According to theoretical analysis and calculation results, the heterogeneous additive NC can shorten the phase transition delay time, form the core vaporization and improve the recovery work of the expander. In the regions far away from the critical point, heterogeneous additive has little impact on the thermal property of the supercritical CO2, such as density, viscosity, specific heat and coefficient of thermal conductivity, etc. The heat transfer of carbon dioxide with trace heterogeneous additive under the pressure of 8.0 MPa was calculated by Gnielinski heat transfer formulation. The results show that the heterogeneous additive NC has little influence on the heat transfer of supercritical CO2, especially far away from the critical point.

关 键 词：超临界CO2异相添加剂 热物性 换热系数 

分 类 号：TK121[动力工程及工程热物理—工程热物理]